[Parasitology] parasite infestation in aquaculture

Dear Simon Jones,
I am working for a fish farming in Corsica. A significant share of our
production corresponds to the exploitation of Argyrosomus regius. The current
production represents 150 tons per year.
Actually, we have a problem with a parasite. The veterinary surgeons indicate
the presence of Monogenea, belonging to the genus Microcotyle, parasitizing
the gills of the fish, it is probably Microcotyle pancerii known in Umbrina
cirrosha. Our losses were significant (14, 5 tons of adults since August 2005
and 3 tons the young specimens only for December 2005).
Mechanical actions were carried out on the exploitation in order to ensure of
the optimal sanitary arrangements: change of the nets, exits of mortalities in
cages every 2 days. The purpose of these actions are to eliminate the eggs
from the parasite which could stagnate in the cages.
The temperature of water is in constant reduction since the beginning of
October. This phenomenon, undoubtedly, contributed to the reduction in
mortalities in particular in the adults but do not seem to have of effect on
the young specimens whose mortalities are in increase.
We are interested today in Praziquantel which is likely to limit the parasitic
infestation. To date, no medicamentous food containing Praziquantel is
known. The product must thus be incorporated in the usual food of fish.
This product is, indeed, a very bitter product that do not appreciate fish.
Additives (Oil of fish, Paraffin oil, vegetable Glycerin, fish Protein) were
tested but none made improvement to the taste of the preparation. The fish
continue to refuse the treatment. The current difficulty is thus to mask the
taste of Praziquantel.
I would like to know if you have any experience and councils in such parasitic
problem? If you know Praziquantel or other product against monogenetic
infestation? If you know additives to mask taste of the product? And finally,
if you know mechanical actions to limit infestation (frequence of change of
net
)?
Our company encounters difficulties today, and we hope that you will be able
to give us some useful information.
Best regards
Sonia Ternengo
Gloria Maris Production
10 cours général Leclerc
20000 Ajaccio
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